Much has been made over the last few days over a video posted on the personal blog of former FishbowlDC editor Patrick Gavin. It features the White House press corps staying seated as Pres. George W. Bush entered the briefing room but standing up when Pres. Barack Obama made a surprise appearance last Friday.

CBS Radio News’s veteran White House correspondent Mark Knoller writes about the video on CBSNews.com. “It’s a long-standing practice for reporters to rise when the president enters the East Room for a news conference, but that hasn’t been the case in the briefing room,” he writes. “The principal reason reporters remained in their seats…was not to block the shot of TV cameramen and still photographers in the back of the room.”

So why stand for Pres. Obama? “When some reporters stood up for President Obama last Friday, they forgot about the needs of their colleagues in the back of the room as well as the less formal atmosphere of the briefing room,” writes Knoller.

Today, ABC’s Jake Tapper tweets about this this video of the press corps standing for Pres. Bush’s final appearance in the briefing room.